This invention relates generally to a method and apparatus for lifting a work implement attached to a work machine and, more particularly, to a method and apparatus for automatically tilting the work implement as the work implement is being lifted.
Work machines, such as wheel loaders, track loaders, and the like, are often used to dig material from a location such as a pile. For example, a wheel loader may be used to dig gravel, sand, dirt, and the like, from a pile for transport and loading somewhere else. The wheel loader typically includes an attached work implement, such as a bucket, to perform the dig operation.
It is usually most efficient when digging from a pile to move the bucket into the material, and then lift the bucket while simultaneously tilting the bucket in a backwards direction, known as xe2x80x9crackingxe2x80x9d the bucket. An optimal amount of material is then captured by the bucket in one efficient series of motions. However, this series of steps requires a skilled operator for smooth and efficient performance, particularly when operating a wheel loader which has separate control levers for lifting and tilting of the bucket.
Advances have been made in automating the dig process of a wheel loader when engaging a pile of material. An exemplary patent with respect to automated digging operations is shown by U.S. Pat. No. 5,974, 352, to Andrew G. Shull. However, automated digging by a wheel loader may not always be desired. In many situations, it would be preferable to continue using a manual system, yet enhance the manual operations with partial automated control for those procedures which require advanced operator skill.
The present invention is directed to overcoming one or more of the problems as set forth above.
In one aspect of the present invention a method for lifting a work implement attached to a work machine is disclosed. The method includes the steps of delivering a lift command to a hydraulic lift circuit, diverting a portion of the lift command to a hydraulic tilt circuit, and responsively tilting the work implement to a rack-back position in cooperation with lifting the work implement.
In another aspect of the present invention an apparatus for lifting a work implement attached to a work machine is disclosed. The apparatus includes an operator controlled lever for delivering a lift command, a hydraulic lift circuit for receiving the lift command and responsively lifting the work implement, a hydraulic tilt circuit, and means for receiving a portion of hydraulic control from the hydraulic lift circuit and responsively delivering the portion to the hydraulic tilt circuit for tilting the work implement to a rack-back position in cooperation with lifting the work implement.